NEC switch - Manual (Page 196)

CHAPTER 14 µµµµPD78F9801
User’s Manual U12978EJ3V0UD
196
(1) Signal conflict
If the dedicated flash programmer (output) is connected to a serial interface pin (input) that is connected to
another device (output), a signal conflict occurs. To prevent this, isolate the connection with the other
device or set the other device to the output high impedance status.
Figure 14-5. Signal Conflict (Input Pin of Serial Interface)
Input pin
Signal conflict
Connection pin of
dedicated flash
programmer
Other device
Output pin
In the flash memory programming mode, the signal output by another
device and the signal sent by the dedicated flash programmer conflict;
therefore, isolate the signal of the other device.
PD78F9801 µ
(2) Abnormal operation of other device
If the dedicated flash programmer (output or input) is connected to a serial interface pin (input or output)
that is connected to another device (input), a signal is output to the device, and this may cause an abnormal
operation. To prevent this abnormal operation, isolate the connection with the other device or set so that the
input signals to the other device are ignored.
Figure 14-6. Abnormal Operation of Other Device
Pin
Connection pin of
dedicated flash
programmer
Other device
Input pin
If the signal output by the PD78F9801 affects another device in the flash
memory programming mode, isolate the signals of the other device.
Pin
Connection pin of
dedicated flash
programmer
Other device
Input pin
If the signal output by the dedicated flash programmer affects another
device in the flash memory programming mode, isolate the signals of the
other device.
PD78F9801
PD78F9801
µ
µ
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